2 Messages
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80 Points
Lightroom: mathematics of Exposure Control
The exposure slider is said to control the exposure of the photo: e.g. a value of +1 should do the same like doubling the exposure time when taking the picture. While the result is visually somehow pleasant, the RGB values in the picture aren't manupulated like mentioned: e.g. an exposure control value +1 should double the XYZ values (XYZ values are those values that can be calculated from the RGB vals using the correct ICC-Profile). The result of "exposure control" is quite far away from doing that. I assume that this behavior is intendet.
But, is there a way to have something like a "real" (mathematically) exposure control? E.g. a linear scaling of the XYZ tone curves?
Thanks for any suggestion.
Edgar
PS I'm using LR as a measurement tool
But, is there a way to have something like a "real" (mathematically) exposure control? E.g. a linear scaling of the XYZ tone curves?
Thanks for any suggestion.
Edgar
PS I'm using LR as a measurement tool
Responses
john_verne
704 Messages
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8.5K Points
8 years ago
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dnicolaescu
677 Messages
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8.7K Points
8 years ago
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rob_cole_2221866
4.5K Messages
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76.3K Points
8 years ago
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tk_images
513 Messages
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11.1K Points
8 years ago
There are hidden tone curves in camera profiles, etc.
You'll have to jump to a number of hoops to get LR to be neutral and then you'll still be facing non-optional auto-this and auto-that behaviour.
I didn't upgrade to LR4 and its patronising attitude towards users that know what they are doing was one of the reasons.
P.S.: If you switch to PV 2010, you practically get LR3 back, but I wonder if there is a way to get rid of the warning triangles that signal that you are not using PV 2012. I wouldn't want them to be in my face all the time.
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edgar_loser_4971428
2 Messages
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80 Points
8 years ago
But I found a workaround using Photoshop:
1. (if not done before) change RGB Format to 16 Bit
2. convert to "own RGB Profile": for this profile I used a gamma of 1.0 (i.e. RGB is linear to XYZ)
3. do the scaling by using Tone Curves
4. convert back to original RGB profile
@TK: I know about "hidden tone curves" of the LR camera profiles. But you can get rid of then using the Adobe DNG Profile editor (free download). Howto can be found here (in german but the pictures may be sufficient):
http://forum.colymp.com/viewtopic.php...
Edgar
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